Deadened crease

ABSTRACT

MALE AND FEMALE CREASING ROLLERS IN PREFERED FORM, AND PROVIDE AN OFFSET AREA EXTENDING LONGITUDINALLY OF THE CRUSHED AREA AT THE CENTER THEREOF, THE PAPERBOARD FOLDING ALONG THE EDGES OF THE OFFSET AREA.   THE PRESENT INVENTION RELATES TO A DEADENED CREASE IN CORRUGATED PAPERBOARD, AND PARTICULARLY A CREASE EXTENDING TRANSVERSELY OF THE CORRUGATIONS. THE CREASE IS FORMED BY CRUSHING A RELATIVELY WIDE AREA OF THE CORRUGATED ALONG THE CREASE, PREFERABLY BETWEEN A PAIR OF MALE CREASING ROLLERS, AND THEN ADDING A NORROWER CREASE ALONG THE CENTER LINER OF THE CRUSHED AREA. THE SECOND CREASE IS FORMED BY

Feb. 20, 1973 w. H. RASMUSSEN 3,717,074

DEADENED GREASE Filed Dec. 4, 1967 INVENTOR 35 WALK-A H. finsmusss/v ATTOR N H4 United States Patent 3,717,074 DEADENED GREASE Walter H. Rasmussen, St. Paul, Minn., assignor to Hoerner-Waldorf Corporation, St. Paul, Minn. Filed Dec. 4, 1967, Ser. No. 687,669 Int. Cl. B31b 1/00 US. Cl. 93-1 G 6 Claims ABSTRACT OF THE DISCLOSURE The present invention relates to a deadened crease in corrugated paperboard, and particularly a crease extending transversely of the corrugations. The crease is formed by crushing a relatively Wide area of the corrugated along the crease, preferably between a pair of male creasing rollers, and then adding a narrower crease along the center line of tne crushed area. The second crease is formed by male and female creasing rollers in preferred form, and provide an offset area extending longitudinally of the crushed area at the center thereof, the paperboard folding along the edges of the offset area.

This invention relates to an improvement in deadened crease and deals particularly with a particular form of crease and a method and apparatus for forming the same.

Corrugated paperboard is often produced in which the 'body of the paperboard is so stiff and rigid that it is difficult to fold along conventional score lines. This is particularly true when the corrugated paperboard in question is what is commonly known as double walled corrugated board which includes two corrugated mediums sandwiched between the liner sheets. Creases of conventional form usually fold readily in one direction, and much less readily in the other. When creases of this type are used to connect the rectangular body walls of a container to their respective closure flaps, the creases are usually arranged so that the flaps will fold inwardly readily to permit the container to be closed. However, in many instances, particularly where the containers are sealed on case sealing equipment, it is necessary to fold the closure flaps outwardly during the filling operation before they are folded inwardly. Difiiculty is often experienced in do ing this.

Attempts have been made to solve-the problem by widening the crease and crushing the corrugated paperboard between two opposed male creasing rollers. However, when this is done, it is difficult to accurately determine just where the actual line of fold will occur. When the flaps are folded, the actual line of fold may be anywhere throughout the width of the wide creases. In some instances, the flaps will fold along a diagonal line across the wide creases. When the flaps are folded into closed position, the actual line of fold may be SQ located that the outer closure flaps may either terminate in spaced relation or else tend to overlap.

I have found that an effective crease may be produced in corrugated paperboard of this type by directing the paperboard through a plurality of creasing stations. In preferred form, the paperboard blanks or webs are first directed between a pair of opposed relatively wide male creasing rollers which are centered in opposed relation. These rollers tend to crush a relatively wide area of the corrugated paperboard into substantially flat form. The blanks or the web next pass between a pair of substantially conventional male and female creasing rollers which are centered with respect to the wide crushed areas which have previously been formed. The male and female creasing rollers form a second crease extending along the center of the crushed area, defining a definite line of fold. Due to the fact that the crushed area does not return to its original form, and is therefore thin as compared with the 3,717,074 Patented Feb. 20, 1973 thickness of the corrugated sheet, the corrugated board may fold in either direction along the center line of the crushed area, or along the second formed crease.

One of the difficulties involved in creasing corrugated board transversely of the corrugations lies in the fact that these creases are usually applied on the corrugator, while the web is hot and rather damp. After a period of time, the blanks dry and stiffen. As a result, when the container is formed and filled, and the flaps folded through ninety degrees to close the container, the folded flaps tend to spring back toward alignment with the container walls, straining the adhesive connection between the flaps or the tape securing the container closed. By deadening the creases in the manner described herein, this spring back tendency is greatly reduced, resulting in a more effective closure.

These and other objects and novel features of the present invention will be more clearly and fully set forth in the following specification and claims.

In the drawings forming a part of the specification,

FIG. 1 diagrammatically illustrates two pairs of creasing rollers successively engaged by the corrugated web or the corrugated blanks.

FIG. 2 is a sectional view on an enlarged scale through a portion of the Web closely adjacent to the first creasing rollers.

FIG. 3 is a view similar to FIG. 2 but showing the web closely adjacent to the second creasing rollers.

FIG. 4 is an enlarged sectional view through the creased sheet.

FIG. 5 is a view similar to FIG. 4 after the sheet has been bent along the fold lines.

FIG. 6 is a view similar to FIG. 5 showing the sheet folded in a reverse direction.

In the formation of containers made of corrugated paperboard, it is usual practice to crease the corrugated web longitudinally of the web and transversely of the corrugations thereof to define the fold lines connecting the body of the container to the upper and lower closure flaps. After the web has been creased, the web is usually cut into blanks of the proper length. These blanks are then usually fed through a printer slotter in a direction parallel to the flutes of the corrugations. In this apparatus, the blanks are normally printed, the fold lines defining the side and end walls are added, and the flap areas are slotted to separate the flaps one from another. FIG. 1 of the drawings diagrammatically illustrates two sets of creasing rollers in tandem arrangement engaging the Web one after the other. The manner of mounting the shafts supporting the creasing roller is not shown as this structure may be varied depending upon whether the web is being creased on the corrugator, or blanks are being creased.

FIG. 1 of the drawings indicates a pair of creasing rollers 10 and 11 mounted upon parallel shafts 12 and 13 above and below the corrugated paperboard web 14. As is indicated in FIG. 2 of the drawings, both the upper creasing roller 10 and the lower creasing roller 11 are what is commonly known to the trade as male creasing rollers, being provided with a relatively wide peripheral flange 15 and 16 thereupon. The flanges 15 and 16 usually of equal width, and are spaced apart a distance substantially equal to the thickness of the paper forming the corrugated web. In the drawings, the web 14 comprises double face corrugated paperboard including an upper liner 17, a lower liner 19, and an intermediate corrugated medium 20, the flutes of which are adhered to the liners 17 and 19. Obviously, the corrugated Web 14 could comprise double wall corrugated paperboard which includes an upper liner, upper corrugated medium, an intermediate liner, a lower corrugatel medium, and a lower liner, the upper and lower corrugated mediums having their flutes adhered to the liners with which they are in contact.

As will be noted in FIG. 2 of the drawings, the upper and lower liners are crushed against the corrugated medium, providing a relatively wide crushed area which is somewhat greater in width than the normal crease.

A second pair of creasing rollers 21 anl 22 are mounted upon vertically spaced shafts 23 and 24 to engage the web 14 after it has been creased by the creasing rollers 10 and 11. As is indicated in FIG. 3 of the drawings, the upper creasing roller 21 comprises what is known as a female creasing roller, and includes a pair of spaced peripheral flanges 25 with a groove 26 therebetween. The lower corrugated roller 22 comprises a male creasing roller and includes a single peripheral flange 27 encircling the roller. As may be seen in FIG. 3, the outer peripheral surfaces 29 of the creasing roller 21 which are outwardly of the flanges 25 may taper somewhat toward their outer ends so as to relieve pressure against the web. The outer surfaces 30 of the male creasing roller 22 may also taper toward their ends to relieve pressure against the under surface of the web out of the actual creasing area.

As is indicated the flanges 25 are spaced apart a distance substantially greater than the width of the male creasing flange 27 so that the paperboard forming the corrugated board may be engaged by the overlapping flanges or the rollers without shearing the sheets. The male creasing roller 27 forces the paperboard into the groove 26 between the flanges 25, while the flanges 25 of the female roller tend to crush the corrugated board against the surfaces 30 of the roller on either side of the flange 27. The outer edges of the flanges 25 are spaced apart a distance somewhat less than the width of the crushed area formed by the flanges 15 and 16, and the flange 27 is centered between the flanges 25 and centered with respect to the crushed area formed by the flanges 15 and 16.

After passing between the two pairs of creasing rollers, the corrugated board appears in section substantially as indicated in FIG. 4 of the drawings. The upper surface of the upper liner 17 is slightly offset upwardly as indicated at 31, and the lower liner 19 is correspondingly upwardly recessed as indicated at 32. The numerals 33 are designed to indicate the sides of the center crease formed by the creasing rollers 21 and 22. The numerals 34 have been applied to FIG. 4 to indicate the sides of the crushed area formed by the flanges 15 and 16. From the points 34 to the points or lines 35, the corrugated paperboard tapers in thickness and outwardly of the lines 35 the corrugated board is of full thickness.

With this arrangement, it has been found that the corrugated board will fold along the narrowly spaced side edges 33 of the center crease much in the manner indicated in FIG. of the drawings, the portions of the paperboard between the crease lines 33 extending diagonally. It has further been found that with this type of crease, the paperboard will fold along these same lines 33 even if folded in a reversed direction as indicated in FIG. 6. As a result, the container flaps may be folded outwardly into a common plane for filling or during the case sealing operation. Many case sealing machines fold the outer two closure flaps outwardly through an angle of 90 degrees before they are folded inwardly to overlie the first folded flaps. The present form of crease permits such reverse folding without changing the actual location of the crease line maintaining the location of the crease when folded back in the proper direction.

In explanation of the operation of the present structure, it should be stated that when the corrugated paperboard is crushed, as by the creasing rollers and 11 there is always some tendency for the outside liners to return to their original position and thus for the liners to spread apart rather than to remain crushed. When the second creasing operation takes place between the male and female rollers 21 and 22, the added crimps or kinks along the lines 33 tend to hold the offset portion between these fold lines flat as illustrated in FIG. 4. The outer portions of the crushed area outwardly of the fold lines 33 tend to spread apart and it will be noted that the liners are spread apart to some extent inwardly of the fold lines 34. When the paperboard is folded along the crease lines, the board will fold along the fold lines 33 rather than along the fold lines 34 due to the separation of the plies inwardly of the fold lines 34, making the board more resistant to folding along the fold lines 34, than along the fold lines 33. It is for this reason that the fold is controlled as described.

When the board is creased as disclosed, the container is deadened by crushing and by the second creasing operation. As a result, the tendency for the flaps to spring back toward alignment with the walls to which they are hinged is greatly reduced, permitting the flaps to be more readily adhered together or taped in closed position.

I claim: 1. A method of creasing corrugated paperboard having parallel liners and at least one corrugated medium therebetween including the steps of:

crushing the corrugated board inwardly from opposite sides between opposed male dies to provide an elongated crushed area the opposite sides of which are between the planes of said parallel liners,

compressing the crushed area between cooperable male and female dies to offset the central portion of the crushed area relative to the remainder thereof and extending longitudinally throughout the length thereof.

2. The process of claim 1 and in which the offset portion is narrow relative to the width of the crushed area.

3. The process of claim 1 and in which the crushed area and offset portion are sequentially formed between creasing rollers.

4. Method of creasing corrugated paperboard having parallel liners and at least one corrugated medium therebetween through the use of two pairs of creasing rollers mounted in alignment on parallel shafts and between which the paperboard is moved, one pair of creasing rollers comprising opposed male creasing rollers and the other pair of creasing rollers comprising cooperable opposed male and female creasing rollers, the method comprising the steps of:

crushing the corrugated paperboard between said male rollers to provide an elongated crushed area extending transversely of the corrugations of the paperboard and olfset inwardly from the parallel surfaces of the paperboard.

creasing the crushed area between the second pair of rollers to offset a portion of the crushed area relative to the remainder thereof.

5. The process of claim 4 and in which said offset portion is narrow relative to the width of said crushed area.

6. The process of claim 5 and in which said ofiset portion is substantially centered relative to said crushed area.

References Cited UNITED STATES PATENTS 286,287 10/1883 Fisher 156-592 1,079,542 11/ 1913 Colpitts 93-1 6 1,144,765 6/1915 Kelleher 93-5-8 ST 1,196,956 9/1916 Kelleher 93-58 ST 2,223,503 12/1940 Wilson 93-581 2,475,868 7/1949 Anderson 93-581 2,759,523 8/4956 Goldstein 93-581 X 2,949,827 8/1960 Kempen 93-58 ST 8,443,489 5/1'969 Watkins 93-581 3,489,067 1/1970 Hallis 93-5-8 ST FOREIGN PATENTS 517,297 2/'1931 Germany 93-58.1

TRAVIS S. MCGEHEE, Primary Examiner UJS. Cl. X.R. 

